Move endpoint cache to a new service.

Problem/ motivation

The responsibility of the iconify service should not include writing to the file system, although it should use a caching system.

Proposed solution

* Create a new service for the cache
* Inject the cache service to the iconify service
* Create proper testing for the new service and clean the ones in the iconify service.

Please check merge request

Thanks for your effort

It will be part of release 1.0.1